This invention relates generally to fuel filter systems for internal combustion engines. More particularly, this invention relates to a modular base for retaining the filter cartridge and a method for manufacturing the modular base.
In fuel filter systems to which the invention relates, such as those disclosed in U.S. Pat. Nos. 5,203,994, 5,302,284 and 5,766,463, a disposable filter cartridge is mounted to a base in such a way that it can be relatively easily removed at pre-established intervals for replacement purposes. The base typically has a pair of coaxial central conduits that provide the fuel inlet and outlet to the filter cartridge. The cartridge may contain a single or multiple stage filter configuration for filtering the fuel. In numerous embodiments the replaceable filter cartridge is suspended below the base, but other orientations are commonly employed. The base is mounted to the vehicle in any of a number of locations depending on the particular application and spatial constraints. The base typically also includes inlet and outlet connectors that may be in the form of posts or other structures which mount fittings to connect input and output lines to the base.
The fuel filter is most commonly mounted in the engine compartment and may be subject to a number of dimensional and headroom constraints depending on the particular vehicle for which the filter assembly is employed. The placement and angular orientation of the inlet and outlet connectors or fittings are often critical for meeting the headroom and optimum system constraints of the application. A bracket typically projects from the base to provide a location for use of mounting hardware to fix the base to the vehicle. The base/vehicle attachment must be able to withstand the vibration and physical shock present in a vehicular environment.
Vehicle manufacturers provide a multitude of custom vehicle configurations to meet consumer demand. Frequently, within a particular base vehicle there are multiple engine types and accessory packages. Each engine type and/or accessory package may require an alternative fuel filtration configuration. Diesel fuel systems may be equipped with pre-heaters and hand primers on the filter base. As a result, there has been a proliferation in the number of filter base configurations necessary to meet the demands of vehicle manufacturers.
Filter bases have typically been cast aluminum or molded plastic units. The molds required to produce alternative configurations are complex and therefore expensive to produce. Each mold frequently includes unique fuel inlet and outlet configurations as well as alternative bracket and filter retention arrangements. In some instances the total quantity of bases having a particular configuration may be quite limited. These factors place a premium on the ability of component manufacturers to produce filter bases configured to vehicle manufacturer specifications quickly and efficiently.
U. S. patent application Ser. No. 60/183,194, assigned to the assignee of the present invention, is directed to a multi-configurable filter base module and manufacturing method therefor. In accordance with that invention, a filter base is manufactured from component parts that are molded separately and assembled to form alternative base configurations as required. A modular configuration enables the component manufacturer to modify a particular aspect of the filter base, such as the bracket or inlet/outlet configuration without producing an entirely new mold. Dramatic improvements in cost-efficiency are possible with a modular base. Certain portions of a plastic base require reinforcement to withstand the stresses placed on the base in the vehicular environment. The mounting structure is particularly vulnerable to stresses from both the mounting hardware and environmental stress. The multi-configurable base module uses split tubular steel sleeve reinforcements within the brackets to enhance the structural integrity of the brackets and their fastening to the engine compartment.
A modular configuration places a premium on the efficiency and reliability of the assembly process to capture potential cost savings. The assembly process preferably requires a minimum of labor intensive steps to produce a fluid-tight filter base of high structural integrity. Assembly using solvent-based or ultrasonic welding can be labor intensive and may be subject to potential inconsistency in the resulting products. Mechanical, i.e., hardware connections between the component parts, while more reliable, can be expensive to implement in terms of time and labor.
Briefly stated, a preferred embodiment of the invention is a modular base for a filter cartridge in which the metal parts necessary for reinforcement of the mounting structure are utilized to form a robust mechanical connection between primary components of the base.
More particularly, a preferred embodiment of the filter base includes a header portion and a communication module. The header portion includes integrally molded mounting bracket structures and defines a cavity for reception of a filter cartridge. An integral retainer as described in U.S. patent application Ser. Nos. 09/356,578 and 09/356,594, assigned to the assignee of the present invention, extends from the header portion. The retaining ring preferably includes a series of axial slots and associated retaining channels. An associated filter cartridge includes a complementary arrangement of radially projecting tabs. The filter cartridge is inserted into the header portion and rotated to engage the tabs in the retaining channels.
The communication module preferably includes structures for providing fluid communication to and from the filter base and attached filter cartridge. These structures include inlet and outlet connectors and at least one conduit projecting into the cavity defined by the header portion. The communication module is configured to be received in the header portion and joined thereto to form a base for a filter cartridge.
The junction between the header portion and communication module includes a mechanical component and a fluid sealing component. An O-ring seal compressed between complementary structures projecting from the header portion and the communication module preferably provides the fluid-sealing component. The O-ring seal is compressed primarily in a radial direction. A yoke on the communication module complements a slot in a pair of header portion mounting brackets to form two cylindrical pathways through the base. A tubular steel compression limiter is inserted through each pathway. Each compression limiter is preferably in the form of a generally cylindrical split pin. The outside surface of each compression limiter is frictionally retained in the mounting bracket and engaged with the associated yoke to exert an axial retention force between the communication module and the header portion.
Since the step of inserting the compression limiter is a necessary step in the manufacturing process, using the compression limiter to join the communication module and header portion does not add an assembly step. The complementary yoke and slot configurations assure proper alignment of the components. No solvents, adhesives or welding are required. The compression limiter is a high strength steel component and therefore provides an extremely reliable connection.
An object of the present invention is to provide a new and improved multi-function filter base which may be assembled in an efficient and low-cost manufacturing process.
Another object of the present invention is to provide a new and improved filter base in which the primary modular components are held together by a necessary reinforcing component.
Another object of the present invention is to provide a new and improved method for manufacturing a filter base in which the primary modular components are attached during an otherwise required assembly step without the use of a dedicated attachment component.
These and other objects, features and advantages of the invention will become readily apparent to those skilled in the art upon reading the description of the preferred embodiments, in conjunction with the attached drawings.